Force feedback actuator for a steering system

Abstract

Force feedback actuator for a steering device (50) of a vehicle, comprising a drive unit (20) and / or a brake unit, and a transmission (1): - a first gear (2) which is provided to be rotatable about a first axis of rotation (R1) and which is designed to couple with a drive unit (20) for torque transmission; - a first intermediate gear (4) which is in tooth engagement with the first gear (2) and is provided to be rotatable about a first intermediate gear rotation axis (Z1); - a second intermediate gear (5) which is in mesh with the first gear (2) and is rotatable about a second intermediate gear rotation axis (Z2); and - a second gear (3), which is designed as an internal gear and which is rotatably arranged about a second axis of rotation (R2) and which is designed for torque-transmitting coupling with an output unit (21), wherein the second gear (3) is in mesh with the first intermediate gear (4) and the second intermediate gear (5), wherein the first intermediate gear (4) is subjected to a first preload force such that the meshing between the first intermediate gear (4) and the first gear (2) and the meshing between the first intermediate gear (4) and the second gear (3) is backlash-free, characterized in that the first intermediate gear (4) is rotatably arranged via a first bearing (6) on a first rotationally and axially fixed bearing journal (8), and wherein the second intermediate gear (5) is rotatably arranged via a second bearing (7) on a second rotationally and axially fixed bearing journal (9),wherein the bearing journals (9) can be inserted into the gearbox housing or alternatively can be formed integrally with the gearbox housing, wherein the gearbox (1) has a first spring device (10) for generating the first preload force and the first axis of rotation (R1) is radially offset or eccentrically arranged relative to the second axis of rotation (R2).

Description

[0001] The present invention relates to a transmission for an actuator, in particular for a force feedback actuator, an actuator and a steering device for a vehicle. State of the art

[0002] Force feedback actuators are a well-known technology. These actuators are designed to generate a force or torque via a drive and / or brake unit, which acts on an output unit as feedback to the user. The user can also apply a force or torque to the output unit itself. In particular, the force feedback actuator can generate a counterforce or counter-torque that opposes the force or torque applied by the user to the output unit. Especially in systems without a mechanical drive, this is the only way for the user to receive haptic feedback about the system's current state or to experience a familiar sensation.A steer-by-wire steering system serves as an example. In this system, the user cannot directly transmit a rotational input applied to the steering wheel to the wheels due to the lack of a mechanical drive. Most users of older vehicles are accustomed to steering systems with a mechanical drive and thus to the resulting steering feel at the steering wheel as the output unit. Since the user receives no direct feedback from the forces acting on the wheels and chassis, such as the restoring force of steered wheels, this feedback is instead generated by the drive unit and thus made perceptible to the user.

[0003] To enable the smallest and most space-saving design of such actuators, gearboxes are integrated between the drive unit and the output unit to achieve the necessary gear ratio. This allows the actuators that generate the counterforce or countertorque to be built smaller. To ensure immediate feedback to the user, a backlash-free transmission path from the drive unit to the output unit is required.

[0004] JP 2003-312486A discloses a vehicle steering device that uses a planetary gear system to reduce the reaction delay and vibrations in the steering wheel caused by backlash between the gears. The sun gear of the planetary gear mechanism acts as a bevel gear and is axially displaceable to eliminate backlash between the sun gear and the planet gear. An exciter exerts an elastic force on the sun gear to push it toward the planet gear. This design improves steering feel by minimizing vibrations caused by wheel interference.

[0005] DE 10 2014 007 606 A1 discloses a reduction device comprising a planetary gear unit, which is particularly capable of compensating for a gap caused by wear of gear teeth. The reduction device includes a sun gear coupled to a hollow motor shaft, as well as a plurality of first and second planet gears mounted in corresponding ring gears. A carrier with coupling holes allows the planet gears to be connected via connecting shafts, the spacing of which varies. Furthermore, a first elastic element is provided, coupled between a connecting shaft and a coupling hole, to support the functionality of the device.

[0006] JP S60 121 350 A discloses a reduction gear that stabilizes the rotational motion of an input shaft by bringing a pair of planet gears into pressure contact with opposing tooth faces of a sun gear and an inner gear when the input shaft is not driven. The design includes an annular base of a support arm rotatably mounted on an output shaft, and a U-shaped bending spring that engages with the planet gear shafts. This arrangement ensures that the support arms are rotated in opposite directions by an equal torque to guarantee the smooth operation of the drive shaft.

[0007] DE 10 2020 211 195 A1 discloses a feedback actuator for a motor vehicle steering system, comprising an electronically controlled steering actuator that acts on the vehicle's steerable wheels. The feedback actuator includes a torque-generating means that exerts a torque on a steering shaft to transmit feedback regarding wheel-road contact to a steering device. The actuator is characterized by a planetary gear set and an electric motor, wherein the electric motor is mechanically engaged with the planetary gear set to transmit the torque to the steering shaft. The invention further relates to a steer-by-wire steering system equipped with such a feedback actuator.

[0008] US Patent 2007 / 0179011A1 discloses a variable-ratio steering device for a motor vehicle. This device comprises an input shaft connected to a steering wheel and a sun gear coaxial with the input shaft, which surrounds the input shaft. Furthermore, two pairs of planet gears are provided, which mesh externally with the sun gear. A first carrier connects the first pair of planet gears and is coupled to the input shaft. A second carrier, which can rotate relative to the input shaft, connects the second pair of planet gears, while an internal ring gear meshes with both pairs of planet gears and is connected to an output shaft.

[0009] DE 10 2012 211 286 A1 discloses a Wolfrom transmission comprising a central sun gear, a ring gear surrounding the sun gear, and planet gears rotatably arranged between them. The planet gears mesh with the ring gear in a radially outer engagement area and with the sun gear in a radially inner engagement area. According to the invention, at least two planet gears are spring-loaded in the circumferential direction of the Wolfrom transmission, so that they are essentially backlash-free when clamped to the sun gear and the ring gear. This arrangement enables backlash-free clamping of the planet gears in the circumferential direction of the transmission.

[0010] JP 3 025 990 U discloses a device for eliminating backlash, comprising a plurality of intermediate gears arranged parallel between a drive gear and a meshing body. Each intermediate gear meshes with both the drive gear and the meshing body. A drive device is also provided that moves and drives the drive gear in the direction of the meshing body. This design enables a cost-effective and simple structure for eliminating backlash.

[0011] DE 2 406 076 A1 discloses a drive device with a reversible output that rotates a turret, such as a gun turret, in two directions. The drive device comprises an output device that can rotate the turret, and two inputs that are selectively driven to achieve the desired direction of rotation. An intermediate gear is provided to compensate for backlash in the coupling between the input gears in neutral and the output gear by applying a preload torque to the input gears in neutral. This ensures that an input gear that was previously in neutral is always ready to transmit the drive without backlash and cause the rotation of the turret.

[0012] There is therefore a need for backlash-free gearboxes for such actuators, with integration into the vehicle's steering system being particularly desirable.

[0013] Against this background, it is an object of the present invention to demonstrate a way to achieve a backlash-free transmission from the drive unit to the output unit. Disclosure of the invention

[0014] These and other problems, which will be mentioned in the following description or which can be recognized by a person skilled in the art, are solved by the subject matter of the independent claim. Advantageous embodiments and further developments can be found in the dependent claims and the following description.

[0015] According to the invention, a force feedback actuator for a steering system of a vehicle with a transmission is disclosed.

[0016] The gearbox features: - a first gear which is designed to be rotatable about a first axis of rotation and which is designed to couple with a drive unit for torque transmission; - a first intermediate gear which is in tooth mesh with the first gear and is provided to be rotatable about a first intermediate gear rotation axis; - a second intermediate gear which is in mesh with the first gear and is rotatable about a second intermediate gear rotation axis; and - a second gear, designed as an internal gear, which is rotatable about a second axis of rotation and is designed for torque-transmitting coupling with an output unit, where the second gear is in mesh with the first intermediate gear and the second intermediate gear, wherein the first intermediate gear is subjected to a first preload force such that the tooth engagement between the first intermediate gear and the first gear and the tooth engagement between the first intermediate gear and the second gear is free of backlash in a first direction of rotation.

[0017] To further describe the design, directions are first defined. These refer to the second gear. As described above, the second gear is designed to rotate about a second axis of rotation. The direction of this second axis of rotation is subsequently referred to as the axial direction. A direction that rotates around the second gear and the second axis of rotation is called the circumferential direction. A direction that extends radially from the second axis of rotation is called the radial direction.

[0018] The second gear can be arranged radially outside the first intermediate gear, the second intermediate gear and the first gear.

[0019] The first preload force acting on the first intermediate gear ensures that the gearbox is free of backlash.

[0020] The first preload force preferably acts by being supported in the tooth meshes, e.g., the tooth flank contacts, between the first gear and the first intermediate gear, and between the second gear and the first intermediate gear, through which the respective tooth meshing occurs in the first direction of rotation. The transmission can be designed so that a slight rotation of the gears can occur until contact is also established in the tooth meshes between the second gear and the second intermediate gear, and between the second intermediate gear and the first gear, through which the respective tooth meshing occurs in a second direction of rotation. The transmission can therefore be designed so that the rotation of the gears can occur to such an extent that the backlash in all tooth contacts is overcome.Thus, backlash-free transmission between the first and second gear is possible for both directions of rotation (backlash-free torque transmission via the first intermediate gear in the first direction and backlash-free torque transmission via the second intermediate gear in the second direction).

[0021] As described above, the second gear is designed as an internal gear or ring gear. The first gear and the intermediate gears are arranged inside the ring gear. This allows for a very compact design of the disclosed transmission in the radial direction of the second gear. A further advantage is that, when using an internal gear, a relatively large gear ratio between the first and second gears can be achieved, thus enabling the drive unit coupled to the first gear to be dimensioned as small as possible.

[0022] Alternatively, the second gear can also be designed as a gear with external teeth, e.g. as a spur gear.

[0023] The intermediate gears can be designed as gears, in particular as spur gears.

[0024] The first gear can be a spur gear. In particular, the first gear can be a pinion, i.e., the smallest gear. This allows for the highest possible gear ratio between the first and second gears, and thus from a coupled drive unit to a coupled output unit. This allows the drive unit to be designed as small as possible.

[0025] The teeth of the first gear, second gear, and intermediate gears can be straight or helical. Other gear configurations are also possible, such as swept-back gears.

[0026] The aforementioned gear meshes are designed to transmit torque. Torque can thus be transmitted from the first gear via the intermediate gears to the second gear.

[0027] In the aforementioned dental interventions, there is in particular contact at the tooth flanks.

[0028] The drive unit can be a motor or include a motor, such as an electric motor. This can be coupled directly or via intermediate elements to the first gear. The drive unit can also include a controllable brake or be designed as such.

[0029] The output unit can be a steering wheel or have a steering wheel. This can be coupled directly or via intermediate elements to the second gear. The torque generated by the drive unit can then be felt by a user or driver as haptic feedback.

[0030] The first and second directions of rotation can be understood as the direction of rotation of the second gear around the second axis of rotation, clockwise and counterclockwise, respectively. Alternatively, the first and second directions of rotation can be understood as the direction of rotation of the first gear around the first axis of rotation, clockwise and counterclockwise, respectively. The intermediate gears, in addition to providing the gear reduction / overdrive function, also allow for a reversal of the direction of rotation between the first and second gears.

[0031] The gearbox preferably has a gearbox housing to protect the gears from dirt and dust and / or to define the position of the axes of rotation. Likewise, other components such as the motor or other displacement devices can be housed in or attached to the gearbox housing.

[0032] Preferably, the transmission is designed as a disc transmission. This means that its axial extent, in particular the extent of the transmission housing, is significantly smaller than its radial extent. For example, the axial extent can be only 20%, preferably only 10%, of the radial extent.

[0033] The gears of the transmission can be made of metal or plastic, with a tooth width > 10 mm being preferred for plastic. The partial use of plastic can improve noise characteristics, as plastic, due to its material damping properties, is a poorer conductor of sound than metal, and the tooth contact is quieter due to its higher compliance.

[0034] According to one embodiment, the second intermediate gear is subjected to a second preload force.

[0035] The second preload force is preferably designed such that the tooth engagement between the second intermediate gear and the first gear and the tooth engagement between the second intermediate gear and the second gear in the second direction of rotation is backlash-free.

[0036] In this way, the backlash-free operation of the gearbox can be established or further improved.

[0037] The first preload force preferably acts in such a way that it is supported in the tooth meshes, e.g., the tooth flank contacts, between the first gear and the first intermediate gear, and between the second gear and the first intermediate gear, through which the respective tooth mesh occurs in the first direction of rotation. The second preload force preferably acts in such a way that it is supported in the tooth meshes, e.g., the tooth flank contacts, between the first gear and the second intermediate gear, and between the second gear and the second intermediate gear, through which the respective tooth mesh occurs in the second direction of rotation. Thus, backlash-free torque transmission between the first and second gears is possible for both directions of rotation (backlash-free torque transmission via the first intermediate gear in the first direction and backlash-free torque transmission via the second intermediate gear in the second direction).

[0038] According to the invention, the first intermediate gear is rotatably arranged on a first bearing journal that is fixed both rotationally and axially via a first bearing. Furthermore, the second intermediate gear is rotatably arranged on a second bearing journal that is fixed both rotationally and axially via a second bearing. The first and second bearings can be designed as rolling bearings, in particular as ball bearings, in order to minimize friction within the gearbox, so that, when used for a force-feedback actuator, no undesirable effects from loosening processes within the bearings occur when a rotational movement begins.

[0039] The bearing journals can be inserted into the gearbox housing (e.g., into a bore in the housing). Alternatively, the bearing journals can be integrally formed with the gearbox housing.

[0040] According to the invention, the transmission has a first spring assembly for generating the first preload force. The transmission can have a second spring assembly for generating the second preload force. Preferably, the first spring assembly is designed to apply the first preload force circumferentially or parallel to a tangent to the circumference of the first or second gear. It is further preferred that the second spring assembly is designed to apply the second preload force circumferentially or parallel to a tangent to the circumference of the first or second gear. The second preload force is preferably directed opposite to the first preload force. In this way, a uniform load is achieved on the corresponding tooth flanks, in which the respective preload force is supported.

[0041] According to one embodiment, the first spring assembly is arranged between the first intermediate gear and an outer bearing race of the first bearing. Alternatively, the first spring assembly is arranged between an inner bearing race of the first bearing and the first bearing journal. If the transmission has a second spring assembly for generating the second preload force, the second spring assembly can be arranged between the second intermediate gear and an outer bearing race of the second bearing. Alternatively, the second spring assembly can be arranged between an inner bearing race of the second bearing and the second bearing journal. The bearings can be designed as rolling bearings with outer and inner rings, with rolling elements located between the rings.

[0042] The spring assembly can be designed as an annular spring element or as a bushing, or may include such a spring element or bushing. The spring assembly, in particular the spring element or bushing, can be made of plastic, an elastomer, or metal, especially steel or spring steel, or may consist of plastic or metal. In particular, the spring element or bushing may have a corrugated surface with which it is in contact with the respective intermediate gear or bearing journal and the respective bearing ring. The corrugated surface can act like a spring and generate the corresponding preload force in the radial direction of the respective bearing journal. If a radial force is exceeded, e.g., caused by tooth contact, this design limits further displacement once the spring surface is compressed.This displacement limitation ensures that the teeth interlock without interference.

[0043] The spring assembly, in particular the annular spring element or the bushing, may include an element for axial retention. This could be, for example, a collar or a flange. This is particularly advantageous in gear teeth (such as helical gears) where an axial force component is introduced into the tooth contact and which ultimately must be supported on the respective bearing journal by the spring assembly.

[0044] It is advantageous to position the spring assembly, in particular the spring element or bushing, axially centrally under the respective intermediate gear to prevent tilting of the intermediate gear. This ensures better acoustics and / or increased rigidity of the gearbox.

[0045] In general, the spring devices can be designed to apply a radial preload force to the intermediate gears.

[0046] At high parking steering torque (> 5 Nm, > 100 N circumferential force), a spring mechanism that actually preloads the corresponding intermediate gear for the opposite direction of rotation can yield, causing a change in tooth contact on that intermediate gear, and both intermediate gears then transmit the torque jointly. This increases the robustness of the transmission.

[0047] According to one embodiment, the axis of rotation of the first intermediate gear is arranged circumferentially offset relative to the center point of the first bearing journal. This means that, for example, in the first intermediate gear, those tooth flanks are pressed against the tooth flanks of the first and second gears by the first preload force, where, in the first direction of rotation, there is tooth engagement (e.g., tooth flank contact) between the first gear and the first intermediate gear, and between the first intermediate gear and the second gear. For example, the aforementioned first spring assembly is designed to allow displacement of the first intermediate gear parallel to the circumferential direction, thus resulting in the offset arrangement.

[0048] Alternatively or additionally, the axis of rotation of the second intermediate gear can be arranged circumferentially offset relative to the center point of the second bearing journal. This means that, for example, in the second intermediate gear, those tooth flanks are pressed against the tooth flanks of the first and second gears by the second preload force, where, in the second direction of rotation, there is tooth engagement, e.g., tooth flank contact, between the first gear and the second intermediate gear, as well as between the second intermediate gear and the second gear. For example, the aforementioned second spring assembly is designed to allow a displacement of the first intermediate gear parallel to the circumferential direction, thus resulting in the offset arrangement.

[0049] If the spring assembly is located between the outer bearing race and the intermediate gear, the preload force will only displace the intermediate gear relative to the bearing journal. If the spring assembly is located between the inner bearing race and the bearing journal, the preload force will displace the intermediate gear and the bearing together relative to the bearing journal.

[0050] According to one embodiment, the first gear and the second gear are arranged coaxially. That is, if the second gear is designed as a ring gear or internal gear, then it is a planetary gear set with the first gear as the sun gear and the intermediate gears as the planet gears, with the planet carrier remaining stationary.

[0051] According to the invention, the first axis of rotation is radially offset or eccentrically arranged relative to the second axis of rotation. This means that the first and second gears are not oriented coaxially to each other. If the second gear is designed as a ring gear or internal gear, the first axis of rotation, and in particular the first gear, can be located in one half of the interior area enclosed by the second gear, when viewed in the axial direction. Furthermore, the two intermediate gear axes of rotation, and in particular both intermediate gears, can be arranged in the same half. In this way, the other half of the interior area enclosed by the second gear is left almost or completely free. This allows, even if the intermediate gears are fixed in position, other components of the steering system or the force feedback actuator, such as cables or lines, to be placed or guided axially in the free or nearly free half.

[0052] The two described halves are divided in a top view by an axis that passes through the axis of rotation of the second gear. A second axis, perpendicular to this first axis and also passing through the axis of rotation of the second gear, further subdivides the interior, creating four quadrants. It is advantageous that the two intermediate gears are positioned in adjacent quadrants, leaving one half, consisting of two quadrants, almost or completely free, thus saving installation space, while the other half contains the intermediate gears and the first gear. If the intermediate gears are arranged symmetrically to the second axis, an equal torque transmission in both directions of rotation is possible.

[0053] According to one embodiment, the gear ratio from the first gear to the second gear is between 3 and 10, in particular between 4 and 9, and further in particular between 5 and 8. These gear ratios are sufficient to allow the use of the smallest possible drive unit.

[0054] Further aspects of the invention are described below. Features relating to these aspects and already described above in connection with the gearbox can also be understood as features of these aspects.

[0055] According to one aspect of the invention, an actuator, in particular a force-feedback actuator for a vehicle steering system, is provided. The actuator comprises a drive unit and / or a brake unit and a transmission as described above, wherein the drive unit is coupled to the first gear of the transmission in a torque-transmitting manner.

[0056] The drive unit can be an electric motor. It can also include or be designed as a controllable brake. The drive unit is designed to apply torque to the first gear in both the first and second directions of rotation. A separate brake unit can be provided additionally or as an alternative.

[0057] It is advantageous if the gearbox or a main bearing of the drive unit is integrated into the drive unit housing. This allows for a space-saving actuator.

[0058] According to one embodiment, the gearbox is mounted on the drive unit. For example, the gearbox can be located on the outer surface of a drive unit housing. In this configuration, the bearing journals of the intermediate gears and / or the bearings of the first or second gear, as described above, can be located on the housing. The gearbox itself can also be enclosed by a gearbox housing that surrounds the gearbox and is connected to the outer surface of the drive unit housing, as described above. Alternatively, the gearbox and the drive unit can be mounted on a common support structure or housed in a common enclosure. Both embodiments allow for the creation of axially compact actuators, enabling the realization of particularly rigid actuators and minimizing bending stresses.In particular, mounting the gearbox on the drive unit housing eliminates one assembly interface compared to a design with separate housings. This design, as well as the design where the gearbox and drive unit are mounted on a common support structure or housed in a single unit, also achieves an integrated design, creating an actuator as a single, integral component.

[0059] According to the invention, a steer-by-wire steering system for a vehicle is disclosed. The steering system comprises a steering element as an output unit and an actuator as described above, wherein the steering element is coupled to the second gear of the transmission in a torque-transmitting manner. The actuator is preferably designed as a force-feedback actuator.

[0060] The steering element can, for example, include a steering wheel or be designed as a steering wheel itself. The axis of rotation of the steering wheel is preferably parallel to the axial direction of the transmission.

[0061] The actuator can be positioned close to or far from the steering element with appropriate mechanical coupling (e.g., with a shaft, particularly a telescopic one, that couples the steering element to the second gear). Such a shaft is not required when the actuator is positioned close to the steering element.

[0062] The drive unit can be positioned between the transmission and the steering unit. Alternatively, the transmission can also be positioned between the drive unit and the steering unit.

[0063] The following is an example of a gearbox as it may be used in a force feedback actuator of a steering system described above: The gearbox (first gear as pinion, second gear as ring gear) has a gear ratio that results from the number of teeth: 103 (ring gear) : 19 (pinion) = 5.42 The number of teeth on pinion:intermediate gear:ring gear in this example is as follows: 19:31:103. The tooth module is 0.9, the axis offset between pinion and ring gear: 15.4 mm

[0064] In general, the inventors recognized that the geometry of the disclosed transmission is essentially determined by the number of teeth on the intermediate gears. Once the gear ratio is fixed—that is, once the number of teeth on the first and second gears is defined—the "number of teeth" parameter of the intermediate gears can be understood as a geometric design parameter. This is because different intermediate gears with different numbers of teeth, and thus different diameters, can be used between the first and second gears, which ultimately also determines the positioning of the intermediate gear rotation axes. This also defines the size and shape of the remaining installation space. Detailed description based on the attached drawings

[0065] Further measures improving the invention are described in more detail below with reference to the figures. It shows: Fig. 1 a schematic representation of a transmission according to the invention, Fig. 2 a view of an intermediate gear and its bearing according to a first aspect, Fig. 3 a view of an intermediate gear and its bearing according to a second aspect, Fig. 4 a spring device, Fig. 5 a perspective view of a gearbox according to the invention, Fig. 6 a cutaway view of the gearbox Fig. 5, Fig. 7 a first steering device, Fig. 8 a second steering device, Fig. 9 a third steering device, Fig. 10 a perspective view of the mounting of a drive unit in a steering device, Fig. 11 an excerpt from Fig. 10 with installed drive unit, Fig. 12 a perspective view of a steering device, and Fig. 13 an embodiment of an actuator.

[0066] The figures are purely schematic and serve only to illustrate the invention. The same elements are identified by the same reference symbols.

[0067] Fig. Figure 1 shows a schematic representation of a transmission according to the invention.

[0068] Shown is a gearbox 1, in particular for a force feedback actuator of a steering system of a vehicle.

[0069] Gearbox 1 features: - a first gear 2, which is provided to be rotatable about a first axis of rotation R1 and which is designed for torque-transmitting coupling with a drive unit (not shown); - a first intermediate gear 4 which is in tooth mesh with the first gear 2 and is provided to be rotatable about a first intermediate gear rotation axis Z1; - a second intermediate gear 5, which is in mesh with the first gear 2 and is provided to be rotatable about a second intermediate gear rotation axis Z2; and - a second gear 3, which is designed as an internal gear and which is rotatable about a second axis of rotation R2 and which is designed for torque-transmitting coupling with an output unit (not shown), wherein the second gear 3 is arranged radially outside the intermediate gears 4, 5 and the first gear 2 and is in tooth mesh with the first intermediate gear 4 and the second intermediate gear 5, wherein the first intermediate gear 4 is subjected to a first preload force, such that the tooth engagement between the first intermediate gear 4 and the first gear 2 and the tooth engagement between the first intermediate gear 4 and the second gear 3 is backlash-free in a first direction of rotation D1, and wherein the second intermediate gear 5 is subjected to a second preload force, such that the tooth engagement between the second intermediate gear 5 and the first gear 2 and the tooth engagement between the second intermediate gear 5 and the second gear 3 in a second direction of rotation D2 is backlash-free.

[0070] The viewing direction here corresponds to the axial direction of the gearbox.

[0071] The preload forces act in the circumferential direction of the second gear 3, so that the first intermediate gear 4 is subjected to the preload force in a first direction of rotation D1 and the second intermediate gear 5 in a second direction of rotation D2. The preload forces are supported by the respective tooth engagements of the intermediate gears 4 and 5 with the first gear 2 and the second gear 3.

[0072] The first intermediate gear 4 is rotatably mounted on a first bearing journal 8, and the second intermediate gear 5 is rotatably mounted on a second bearing journal 9. A first rolling bearing 6, comprising an outer bearing ring 6.1 and an inner bearing ring 6.2, is located between the first intermediate gear 4 and the first bearing journal 8. A second rolling bearing 7, comprising an outer bearing ring 7.1 and an inner bearing ring 7.2, is located between the second intermediate gear 5 and the second bearing journal 9.

[0073] A spring assembly (not shown) is provided between the first intermediate gear 4 and the first bearing journal 8 and between the second intermediate gear 5 and the second bearing journal 9.

[0074] The respective bearing journal 8, 9 is not positioned coaxially with the actual center of rotation of the first or second intermediate gear 4, 5. Instead, the center of the respective bearing journal 8, 9 and the corresponding intermediate gear rotation axis Z1, Z2 diverge radially. This is indicated by the four dashed lines, which mark the center of the respective bearing journal 8, 9 and the corresponding intermediate gear rotation axis Z1, Z2 in pairs. This offset creates a preload force in the spring assembly, which is supported in the tooth contacts as described above.

[0075] Typical values ​​for the offset are 0.1–0.3 mm. With a tooth module of 0.9 mm, the offset is 0.2 mm.

[0076] The preload force can be 20-200 N.

[0077] With a spring constant of 1000 N / mm, the above-mentioned offset of 0.2 mm results in a preload force of 200 N.

[0078] A horizontal axis A and a vertical axis B are also shown. An advantage of the arrangement shown here is that all gears within the second gear 3 are located above axis A. This means that there is a free area below axis A within the second gear 3, in which components, cables, or lines, e.g., for the steering system, can be routed. This area remains clear during operation because the first gear 2 and the intermediate gears 4 and 5 are stationary. Furthermore, it can be seen that the intermediate gears 4 and 5 are arranged symmetrically to the vertical axis. In this way, an equal gear ratio between the first and second gears 2 and 3 is achieved in both directions of rotation D1 and D2.

[0079] According to an embodiment of the invention not shown, only one of the intermediate gears 4, 5 can be subjected to a corresponding preload force. If, for example, only the first intermediate gear 4 is subjected to the (first) preload force, then, in the case of the second intermediate gear 5, which is not provided with a spring device between the second bearing journal 9 and the intermediate gear 5, there is no offset between the intermediate gear rotation axis Z2 and the center of the second bearing journal 9. The support of the (first) preload force is now achieved, for example, by a rotation.of the second gear 3, so that in the tooth mesh between the first gear 2 and the first intermediate gear 4 and the first intermediate gear 4 and the second gear 3 there is a tooth flank contact for the first direction of rotation D1, while in the tooth mesh between the first gear 2 and the second intermediate gear 5 and the second intermediate gear 5 and the second gear 3 there is a tooth flank contact for the second direction of rotation D2.

[0080] Fig. Figure 2 shows a view of an intermediate gear and its bearing according to a first aspect.

[0081] On the left is an intermediate gear 4, 5, which is joined with a bearing 6, 7. On the right is an exploded view showing, in addition to the bearing 6, 7, a spring assembly 10, 11 and a bearing journal 8, 9.

[0082] It can be seen here that the bearing 6, 7, which is designed as a rolling bearing, is positioned with its inner ring 6.2, 7.2 on the bearing journal 8, 9. The spring device 10, 11, which here is designed as an axially extended bushing, is provided between the outer bearing ring 6.1, 7.1 of the bearing 6, 7 and the intermediate gear 4, 5.

[0083] With the bearing journal 8, 9 stationary, the intermediate gear 4, 5 is preloaded against the teeth of the first and second gears (both not shown here) by the elastically deformed spring assembly 10, 11, since the bearing journal 8, 9 is positioned such that its center does not correspond to the center of rotation of the intermediate gear 4, 5. This center of rotation results from the meshing of the intermediate gear 4, 5 with the first and second gears. This preload ensures backlash-free torque transmission via the intermediate gear 4, 5 in either direction of rotation.

[0084] Fig. Figure 3 shows a view of an intermediate gear and its bearing according to a second aspect.

[0085] On the left is an intermediate gear 4, 5, which is joined to a bearing 6, 7. Additionally, a bearing journal 8, 9 is shown in its installed position. On the right is an exploded view showing, in addition to the bearing 6, 7 and the bearing journal 8, 9, a spring assembly 10, 11.

[0086] It can be seen here that the bearing 6, 7, which is designed as a rolling bearing, is positioned with its inner ring 6.2, 7.2 on the bearing journal 8, 9, with the spring assembly 10, 11 positioned between the inner ring 6.2, 7.2 and the bearing journal 8, 9. The intermediate gear 4, 5 is provided on the outer bearing ring 6.1, 7.1 of the bearing 6, 7. The spring assembly 10, 11 is designed here as an axially extended bushing.

[0087] With the bearing journal 8, 9 stationary, the intermediate gear 4, 5 is preloaded against the teeth of the first and second gears (both not shown here). This preload is caused by the elastically deformed spring assembly 10, 11, since the bearing journal 8, 9 is positioned such that its center does not correspond to the center of rotation of the intermediate gear 4, 5. This center of rotation results from the meshing of the intermediate gear 4, 5 with the first and second gears. This preload ensures backlash-free torque transmission via the intermediate gear 4, 5 in either direction of rotation.

[0088] Fig. Figure 4 shows a spring device. This is designed as a bushing and has circumferential waves. These can deform elastically as described above. Fig. 2 and Fig. 3 described, so that the preload force can be generated.

[0089] The spring assembly may have a locking element against axial displacement, such as a collar or a shoulder, to absorb axial forces from the tooth engagement and to prevent axial displacement.

[0090] Fig. 5 a perspective view of a gearbox according to the invention and Fig. Figure 6 shows a cutaway view of the gearbox. Fig. 5.

[0091] Shown is a gearbox 1 with a first gear 2 and a second gear 3, as well as a first intermediate gear 4 and a second intermediate gear 5. Essentially, this gearbox 1 corresponds to the gearbox described in Fig. 1 is shown.

[0092] Additionally, a bearing 22 is shown here, which can be used to support a drive unit or its shaft. As in Fig. As can be seen in Figure 6, the bearing 22 can be positioned directly on the gearbox 1 or directly on the first gear 2, which allows for a gearbox 1 that is as short as possible in the axial direction.

[0093] Fig. Figure 7 shows a first steering device.

[0094] A schematic representation of a first steering device 50 is shown. This has a power output unit 21 on the right, here a steering wheel, via which a user can receive force or torque feedback.

[0095] On the left is an actuator 40, e.g. a force feedback actuator, which has a gearbox 1 as described above and a drive unit 20 that is coupled to the first gear 2 in a torque-transmitting manner.

[0096] A telescopic steering shaft 24 is provided between the output unit 21 and the gearbox 1, which is guided in a telescopic outer tube.

[0097] In this way, a steering wheel-remote actuator 40 can be positioned and connected to the steering wheel.

[0098] Are the first gear 2 and the intermediate gears 4, 5 as in Fig. If arranged in 1, the drive unit 20 can also be positioned so that the area under axis A is in Fig. Space 1 remains free as a construction area. This area is located above the first gear 2 in the illustration.

[0099] Not shown is another possible way to position the actuator 40. In this embodiment, the actuator 40 is mirrored along a horizontal line compared to the illustration shown. This means that the drive unit 20 and the first gear 2 are located in the upper part of the illustration. Therefore, installation space below the drive unit 20 can now remain free.

[0100] Fig. Figure 8 shows a second steering device.

[0101] Unlike Fig. Actuator 40, for example a force feedback actuator, is positioned close to the steering wheel. This eliminates the need for the steering shaft 24. The telescopic outer tube 23 can still be used to adjust the position of the output unit 21 or the steering wheel relative to a user or driver.

[0102] In the Fig. 7 and Fig. Figure 8 shows that the gearbox 1 is positioned between the output unit 21 and the input unit 20. The housing of the input unit 20 can form part of the housing of the gearbox 1. In contrast, Figure 8 shows that... Fig. 9 a third steering device in which the drive unit 20 is positioned between gearbox 1 and output unit 21. Here, the drive unit 20 can be partially mounted in gearbox 1 or on the first gear 2.

[0103] Each steering device allows the offset positioning of the drive unit 20, so that installation space is kept free (under axle A in Fig. 1).

[0104] Fig. Figure 10 shows a perspective view of the installation of a drive unit in a steering system and Fig. Figure 11 shows an excerpt from Fig. 10 with integrated drive unit 20. This is essentially a configuration that is derived from Fig. Figure 9 corresponds to this. Instead of a steering wheel, a steering wheel bearing 25 is shown here. This is fixed and allows rotation of a steering wheel (not shown) of the steering mechanism. The connection of the steering wheel to the second gear 3 for torque transmission is not shown here. The connection extends past the drive unit 20 and is coupled to the second gear 3 of the gearbox 1. The drive unit 20 is positioned between the steering wheel bearing 25 and the gearbox 1. It faces away from the steering wheel bearing 25 and engages with the first gear of the gearbox 1, allowing the bearing (not shown) of the first gear 2 to serve as the main bearing for the drive unit 20. In this way, a shorter axial design can be achieved.

[0105] The in the Fig. 10 and Fig. The embodiment shown in Figure 11 depicts the positioning of the gearbox 1 and the drive unit 20 on a common support structure, namely a telescopic support structure such as the one shown in Figure 11. Fig. 9 shown in the casing tube. This allows for an integral design of the actuator or the stiffest possible design and connection of the drive unit 20 to the gearbox 1.

[0106] Fig. Figure 12 shows a perspective view of a steering device 50, with a force feedback actuator 40 mounted close to the steering wheel, positioned directly behind the output unit 21 or the steering wheel. The steering wheel itself is adjustable in position by means of the telescopic outer tube. The steering device shown can be compared to a steering device according to the Fig. 8 or Fig. 9 correspond.

[0107] Fig. Figure 13 shows another embodiment of an actuator.

[0108] A sectional view is shown in which the gearbox 1 is mounted on the housing of the drive unit 20. The bearing 22 (main bearing) of the drive unit 20, which is configured here as an electric motor, is located in a housing wall of the drive unit 20. This housing wall also carries the bearing journals of the intermediate gears on its outer surface; only the second intermediate gear 5 is shown here. The first gear 2 is a pinion mounted on the shaft of the drive unit 20. The second gear 3 is a ring gear mounted on the housing of the drive unit 20 by means of a rolling bearing, which circumferentially surrounds the housing of the drive unit 20.

[0109] This actuator design, particularly for a force-feedback actuator, allows for a rigid and compact construction. Furthermore, it creates an integral component with the actuator, and the shared use of the drive unit housing 20 provides a mounting interface, unlike separately designed housings. The actuator can be mounted close to or far from the steering wheel. The gearbox 1 can also be covered by a gearbox housing that connects to the drive unit housing 20. Reference symbol list 1 gearbox 2 first gear 3 second gear 4 first intermediate gear 5 second intermediate wheel 6 first camp 6.1 Outer bearing ring (first bearing) 6.2 Inner bearing ring (first bearing) 7 second camp 7.1 Outer bearing ring (second bearing) 7.2 Inner bearing ring (second bearing) 8 first bearing journal 9 second bearing journal 10 first spring assembly 11 second spring assembly 20 drive unit 21 Output unit 22 warehouses 23 Sheathing tube 24 Steering shaft 25 steering wheel bearings 40 actuator 50 Steering device A horizontal axis B vertical axis D1 first direction of rotation D2 second direction of rotation R1 Rotation axis (first gear) R2 Rotation axis (second gear) Z1 first intermediate gear rotation axis Z2 second intermediate gear rotation axis

Claims

[1] Force feedback actuator for a steering device (50) of a vehicle, comprising a drive unit (20) and / or a brake unit, and a transmission (1): - a first gear (2) which is provided to be rotatable about a first axis of rotation (R1) and which is designed to couple with a drive unit (20) for torque transmission; - a first intermediate gear (4) which is in tooth engagement with the first gear (2) and is provided to be rotatable about a first intermediate gear rotation axis (Z1); - a second intermediate gear (5) which is in mesh with the first gear (2) and is rotatable about a second intermediate gear rotation axis (Z2); and - a second gear (3), which is designed as an internal gear and which is rotatable about a second axis of rotation (R2) and which is designed for torque-transmitting coupling with an output unit (21), wherein the second gear (3) is in tooth mesh with the first intermediate gear (4) and the second intermediate gear (5), wherein the first intermediate gear (4) is subjected to a first preload force so that the tooth mesh between the first intermediate gear (4) and the first gear (2) and the tooth mesh between the first intermediate gear (4) and the second gear (3) is backlash-free, characterized by, wherein the first intermediate gear (4) is rotatably arranged via a first bearing (6) on a first rotationally and axially fixed bearing journal (8), and wherein the second intermediate gear (5) is rotatably arranged via a second bearing (7) on a second rotationally and axially fixed bearing journal (9), wherein the bearing journals (9) may be inserted into the gearbox housing or alternatively may be integrally formed with the gearbox housing, wherein the gearbox (1) has a first spring device (10) for generating the first preload force and the first axis of rotation (R1) is radially offset or eccentrically arranged relative to the second axis of rotation (R2). [2] Force feedback actuator according to claim 1, wherein the second intermediate wheel (5) is subjected to a second preload force. [3] Force feedback actuator according to claim 1 or 2, comprising a second spring device (11) for generating the second preload force. [4] Force feedback actuator according to claim 3 in combination with claim 1, wherein the first spring assembly (10) is arranged between the first intermediate gear (4) and an outer bearing ring (6.1) of the first bearing (6), or wherein the first spring assembly (10) is arranged between an inner bearing ring (6.2) of the first bearing (6) and the first bearing journal (8), and / or wherein the second spring assembly (11) is arranged between the second intermediate gear (5) and an outer bearing ring (7.1) of the second bearing (7), or wherein the second spring assembly (11) is arranged between an inner bearing ring (7.2) of the second bearing (7) and the second bearing journal (9). [5] Force feedback actuator according to any one of claims 1 to 4, wherein the intermediate wheel rotation axis (Z1) of the first intermediate wheel (4) is arranged circumferentially offset relative to a center point of the first bearing journal (8), and / or wherein the intermediate wheel rotation axis (Z2) of the second intermediate wheel (5) is arranged circumferentially offset relative to a center point of the second bearing journal (9). [6] Steering device (50), in particular steer-by-wire steering device, for a vehicle, comprising: a steering element as a power output unit (21), and a force feedback actuator according to any of the previous claims, wherein the steering element is coupled to the second gear (3) of the transmission (1) in a torque-transmitting manner.

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